Hydro-electric generation in the past has focussed on mega-projects, where massive water flows caused by natural features such as waterfalls, or by man made structures such as huge dams, were used to drive massive turbines usually of the Francis type which in turn generated large amounts of electricity for distribution over wide areas. It has been apparent for many years that the availablity of water falls of flows of this magnitude have all been identified and all available use has been made of them.
The future of large scale electric power generation now depends almost exclusively on fossil fuels, or nuclear energy. These are both energy sources with high levels of pollution and contamination. They are also energy sources which have a reasonably predictable short lifespan after which they will have been consumed, and will not be available to future generations of people. Wind power and solar collectors have not proven an acceptable alternative. Recently more attention has been given to small scale electrical generation. It has numerous attractive advantages. It does not require transmission over long distances, with its resultant large power losses.
Small scale generation does not require the erection of large generating plants which are unsightly and unpopular, or the erection of transmission towers and high voltage transmission wires which are costly, unsightly, and are widely believed to be a health hazard for those nearby, and does not involve the consumption of rapidly dissappearing fuel sources, or the creation of large scale pollution or contamination. Studies have shown that small scale power generation can make major reductions in the power generating needs of large utilities, and indeed systems are already available by which small scale generators, which may generate surplus power, can feed that surplus back into the main power distribution grids, and thus actually reduce the load on the major power generating systems.
These smaller scale systems have to a large extent been based either on wind power or solar collectors. Both are somewhat unreliable, being highly seasonal in output, especially in the case of solar collectors, which produce the least power in the colder months when power demand is highest, and which are less efficient in northern, colder climates due to shorter periods of sunshine. Windpower is suitable only in certain specialised areas where strong winds are fairly constant. Water power for smaller scale generation has largely been ignored due to the tendency of persons to think only in terms of massive turbines for large hydroelectric projects.
However the fact cannot be disputed that there are a very large number of streams and small rivers which do have significant water flows, and water drops. These could be employed, given a suitable design of low speed turbine capable of developing power at lower rotational speeds and using these more modest water flows.